Throughout the discussion, although “OLED” is in places called out specifically, an “Organic Light Emitting Diode” (OLED) is regarded as a type of “Light Emitting Diode” (LED). The term “inorganic-LED” is used to specifically signify traditional LEDs made of non-organic materials such as silicon, indium-phosphide, etc. FIG. 1 depicts a visual classification representation showing inorganic-LEDs and Organic Light Emitting Diodes (OLEDs) as mutually-exclusive types of Light Emitting Diodes (LEDs).
Color inorganic-LED array displays are currently employed in “LED TV” products and road-side and arena color-image LED advertising signs.
Color OLED array displays have begun to appear in cellphones, smartphones, and Personal Digital Assistants (“PDAs”) manufactured by Samsung, Nokia, LG, HTC, Phillips, Sony and others. Color OLED array displays are of particular interest, in general and as pertaining to the present invention, because:                They can be fabricated (along with associated electrical wiring conductors) via printed electronics on a wide variety of surfaces such as glass, Mylar, plastics, paper, etc.;        Leveraging some such surface materials, they can be readily bent, printed on curved surfaces, etc.;        They can be transparent (and be interconnected with transparent conductors);        Leveraging such transparency, they can be:                    Stacked vertically,            Used as an overlay element atop an LCD or other display,            Used as an underlay element between an LCD and its associated backlight.LEDs as Light Sensors                        
Light detection is typically performed by photosite CCD (charge-coupled device) elements, phototransistors, CMOS photodetectors, and photodiodes. Photodiodes are often viewed as the simplest and most primitive of these, and typically comprise a PIN (P-type/Intrinstic/N-type) junction rather than the more abrupt PIN (P-type/N-type) junction of conventional signal and rectifying diodes.
However, virtually all diodes are capable of photovoltaic properties to some extent. In particular, LEDs, which are diodes that have been structured and doped specific types of optimized light emission, can also behave as (at least low-to moderate performance) photodiodes. In popular circles Forrest M. Mims has often been credited as calling attention to the fact that that a conventional LED can be used as a photovoltaic light detector as well as a light emitter (Mims III, Forrest M. “Sun Photometer with Light-emitting diodes as spectrally selective detectors” Applied Optics, Vol. 31, No. 33, Nov. 20, 1992), and as a photodetector LEDs exhibit spectral selectivity associated with the LED's emission wavelength. More generally, inorganic-LEDs, organic LEDs (“OLEDs”), organic field effect transistors, and other related devices exhibit a range of readily measurable photo-responsive electrical properties, such as photocurrents and related photovoltages and accumulations of charge in the junction capacitance of the LED.
Further, the relation between the spectral detection band and the spectral emission bands of each of a plurality of colors and types of color inorganic-LEDs, OLEDs, and related devices can be used to create a color light-field sensor from, for example, a color inorganic-LED, OLED, and related device array display. Such arrangements have been described in pending U.S. patent application Ser. No. 12/419,229 (priority date Jan. 27, 1999), pending U.S. patent application Ser. No. 12/471,275 (priority date May 25, 2008), and in pending U.S. patent application Ser. No. 13/072,588 and U.S. 61/517,454. The present invention expands further upon this.
Pending U.S. patent application Ser. No. 12/419,229 (priority date Jan. 27, 1999), Ser. No. 12/471,275 (priority date May 25, 2008), U.S. Ser. No. 13/072,588, and U.S. 61/517,454 additionally teaches how such a light-field sensor can be used together with signal processing software to create lensless-imaging camera technology, and how such technology can be used to create an integrated camera/display device which can be used, for example, to deliver precise eye-contact in video conferencing applications.
In an embodiment provided for by the invention, each LED in an array of LEDs can be alternately used as a photodetector or as a light emitter. At any one time, each individual LED would be in one of three states:
A light emission state,
A light detection state,
An idle state.
as may be advantageous for various operating strategies. The state transitions of each LED may be coordinated in a wide variety of ways to afford various multiplexing, signal distribution, and signal gathering schemes as may be advantageous.
Leveraging this in various ways, in accordance with embodiments of the invention, array of inorganic-LEDs, OLEDs, or related optoelectronic devices is configured to perform functions of two or more of:
a visual image display (graphics, image, video, GUI, etc.),
a (lensless imaging) camera,
a tactile user interface (touch screen),
a proximate gesture user interface.
These arrangements further advantageously allow for a common processor to be used for two or more display, user interface, and camera functionalities.
The result dramatically decreases the component count, system hardware complexity, and inter-chip communications complexity for contemporary and future mobile devices such as cellphones, smartphones, PDAs, tablet computers, and other such devices.
In cases where a user interface is incorporated, the RF capacitive matrix arrangements used in contemporary multi-touch touchscreen are replaced with an optical interface.
Further, the integrated camera/display operation removes the need for a screen-direction camera and interface electronics in mobile devices. The integrated camera/display operation can also improve eye contact in mobile devices.